This proposal requests continued support for the MIT/Harvard Center for Magnetic Resonance (CMR) located at the Francis Bitter Magnet Laboratory, MIT (Grant RR-009995-22). During the coming five year grant period we plan significant upgrades of existing equipment, acquisition of new instrumentation, and research initiatives in several new areas: (1) The 19 spectrometers currently operating in the facility will continue to be improved with new transmitters, receivers, pulse programmers, computers, etc. (2) The facility will expand with the addition of four instruments: (a) a 250 GHz EPR/ENDOR spectrometer, (b) a 375 MHz DNP spectrometer, and (c) a 750 MHz/89 mm magnet and console will be completed, and (d) we plan to pursue acquisition of a 900 MHZ magnet and console. (3) New and continuing areas of interest in the core research program include: (a) RF gradient enhanced spectroscopy, (b) high resolution solution NMR spectroscopy of proteins and protein/nucleic acid complexes, (c) imaging of solids, (d) structural studies of solids via dipolar recoupling techniques, (e) structural studies of large proteins including enzyme/substrate inhibitor complexes, beta- amyloid, bacteriorhodopsin, and halorhodopsin, (f) CW and pulsed dynamic nuclear polarization, and (g) high frequency CW and pulsed EPR and ENDOR studies of paramagnetic enzymes and enzyme inhibitor complex, (4) The collaborative research effort will grow significantly and will include Solution NMR investigations of (a) drug induced DNA degradation (Stubbe), (b) human sarcomas (Singer), (c) intermediates in protein folding (KEMP), (D) combinatorial carbohydrate libraries (Seeberger), (3) ferrodoxins (Pochapsky), (f) protein dynamics (Kern), and (g) structural studies of a number of proteins (Wagner). Imaging studies will include development of a number of new techniques and investigation of new systems. (5) The service component of the facility remains an important function as is evident by the 14 proposals from outside investigators who have or plan to use the facility frequently. (6) Plans for training and dissemination include course work in magnetic resonance seminars, and publication in scholarly journals.